SAP Note 12825 - Installation of two R/3 Systems on one host

Symptom:

Two R/3 systems based on INFORMIX are to be installed on one host.
Because there is only one UNIX user 'informix' for both systems, you need to note the following:

Cause and prerequisites

The user and group 'informix' are necessary on Unix level to operate the INFORMIX database.
If serveral database systems are installed then the same user 'informix' has administration rights for all systems. Which databases the administration tools access can be controled via the environment variables.

If several INFORMIX OnLine DBS are started at the same time on one computer, each must possess a different server number. This is accomplished with the SERVERNUM parameter in the appropriate configuration file ONCONFIG.

The following assumes that one system has already been installed (for example, P21) and a second additional system should be installed (for example, T21).

Solution

1. If the installed system is running, stop it completely ("stopsap").

2. Change the SEVERNUM parameter in the ONCONFIG file. (/informix/P21/etc/onconfig..p21). (for example from 0 to 1.)

3. Install the second R/3 system (for example, T21) as usual with the assistance of the appropriate installation tool.

Note the following points:

a) Use the suggested values for the numeric ID of the user 'informix' and 'sapr3' and all groups ('sapsys'...).

b) Let the system choose a free numeric ID for the user adm (In example 't21adm') or allocate a free user ID.

c) Make sure not to refer any "raw-devices" of the existing installation when you create the sapdata structure.

4. Delete all data from the home directory of the user 'informix', particularly all files whose name begin with a point ('.').
This makes sure that the user 'informix' has no environment set after logging on and in turn cannot administer either of the database systems (and certainly cannot unintentionally administer the incorrect one).

5. If this does not happen, then distribute passwords for both users 'p21adm' and 't21adm' on Unix level.

To administer the database system proceed as follows:
To administer the system , log on to Unix level as adm.
For cases when 'informix' user rights are required, enter the 'su informix' command. (without a minus sign between 'su' and 'informix' therefore NOT 'su - informix')
After the password query (Unix password of the 'informix' user), a shell is started with 'informix' authorizations.

In contrast to the procedure described earlier, this procedure offers the following advantages:

1. You are less likely to mix up the administered database system.

2. A change in the UNIX shell's behaviour (sources from $ENV by sub-shells that are not interactive) or a change in the shell can no longer influence the functioningof the the administration tools.

3. Editing the logon scripts is no longer required.

The disadvantage of this procedure is that two passwords (for 'adm' and 'informix') are required for the administration of the database system.

Note
In principle it is still possible for the 'informix' user to administer both database systems. For example, after logging on to the system for example, the user can access the files .dbenv_.[c]sh and .sapenv_.[c]sh from home directory of the particular adm sources and finally access the system's database system .
Because each of the adm users needs the 'informix' password, each can access the other SID's database system.
This procedure is therefore insufficient if you want to perform the administration of several systems.

Additional key words

R3INST R3SETUP .dbenv .sapenv installation

Key Word: Installation